Momentary contact single pole switch

ABSTRACT

A momentary contact pushbutton single pole switch is provided by a substrate such as a printed circuit board having contacts formed thereon, a curved conductive spring washer and a nonconductive button having two integral legs or projections that extend through a slot in the curved spring washer and further through a similar slot in the printed circuit board. The pushbutton is retained by a tab on the end of each leg which extends beyond the edge of the slotted hole in the printed circuit board.

United States Patent 1191 Comer Dec. 23, 1975 [75] Inventor: Jerry L. Comer, Richardson, Tex.

[73] Assignee: Texas Instruments Incorporated,

Dallas, Tex.

[22] Filed: Sept. 16, 1974 [21] Appl. No.: 506,485

[52] US. Cl. 200/159 R; 200/159 B; 200/340; 200/5 A [51] Int. Cl. H01H 3/12; I-IOlI-I 13/52 [58] Field of Search 200/159 B, 292, 159 A,

200/159 B, 159 R, 275, 340, 5 A, 5 R

[56] References Cited UNITED STATES PATENTS 3,141,945 7/1964 Juggins 200/159 R 3,367,206 2/1968 Moody 200/340 X 3,544,987 2/1967 McMann, Jr. et al. 200/283 X 3,691,324 9/1972 Brantingson 200/5 A X 3,705,276 12/1972 Seeger, Jr. et al. 200/292 X MOMENTARY CONTACT SINGLE POLE SWITCH 3,721,778 3/1973 Seeger, Jr. et al. 200/159 B X 12/1974 Boulanger 200/5 A X OTHER PUBLICATIONS Taris, Keyboard, IBM Tech. Discl. Bulletin, Jan. 1966, Vol. 8, No. 8, p. 1064.

Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. Smith Attorney, Agent, or Firm-Harold Levine; Edward J. Connors, Jr.; Stephen S. Sadacca [57] ABSTRACT 11 Claims, 7 Drawing Figures U.S. Patent Dec. 23, 1975 Sheet 1 0f 2 MOMENTARY CONTACT SINGLE POLE SWITCH This invention relates to momentary contact single pole pushbutton switches and, in particular, to such switches mounted on a substrate such as a printed circuit board for establishing positive electric contact in response to actuation.

A typical momentary contact single pole pushbutton switch consists of a pushbutton actuator which bears on a contact that is normally held away from two terminals by a spring bias member, the various elements being contained in and supported by a housing which may be made of one or several pieces. Depressing the pushbutton compresses the spring and causes the contact to complete an electrical circuit between the two terminals. When the depressed pushbutton is released, the spring bias member returns the contact and pushbutton to their normal positions, opening the electrical circuit. In such switches, the spring and contact are usually separate members and the pushbutton actuator must be supported by a housing.

In another type of switch such as those described and claimed in US. Pat. Nos: 3,684,842, Pushbutton Keyboard Switch Assembly with Improved Over Center Diaphragm Contact; 3,725,907, Pushbutton Keyboard System; 3,611,357, Pushbutton Keyboard Assembly; 3,783,205, Keyboard Switch Matrix Assembly with Improved Guide Means for Reducing Transfer of Bounding Motion to Movable Conductor; 3,707,609, Diaphragm Pushbutton Switch Array for Keyboards; 3,806,673, Pushbutton Keyboard Switch Assembly with Improved Disc Spring Contact and Printed Circuit Structure; and 3,808,384, Pushbutton Keyboard System, switches are disclosed utilizing a one piece spring contact; however, the pushbutton actuator must still be restrained by a suitable support. In such switches, for example, the pushbutton actuator is restrained by a suitable support such that it is positioned above a cupped bimetal disc which is located in a pocket formed by an insulator, flexible membrane and a printed wiring board. The disc is supported by two staples, for example, which feed through the printed circuit board and are electrically connected to its circuitry. The center of the disc is above, but not normally contacting, another staple which is electrically connected to other circuitry on the printed circuit board. Depressing the pushbutton deforms the cup-shaped spring disc such that the disc contacts the staple under its center which completes an electrical circuit between the center staple and the two support staples and their respective associated circuitry. When the depressed pushbutton is released the spring action of the disc returns the button to its normal position and opens the electrical circuit.

It is an object of the present invention to providean improved and greatly simplified momentary contact single pole pushbutton switch.

It is another object of the invention to provide a momentary contact pushbutton single pole switch in which the pushbutton actuator requires no support housing.

It is still another object of the invention to provide a momentary contact single pole pushbutton switch which does not require a separate spring and actuator contact.

It is still a further object of the invention to provide a method for manufacturing a momentary contact single pole pushbutton switch which is greatly simplified.

An advantage of the pushbutton switch and method of manufacturing such switch in accordance with the present invention is that its simplification substantially reduces the cost of manufacturing such pushbutton switches.

These and other objects and advantages are provided by a momentary contact single pole pushbutton switch embodied in the present invention which includes a pushbutton actuator formed of a non-conductive material having two integral legs or projections which extend through a slot in a curved wave-shaped conductive spring washer and further through a similar slot in a substrate such as a printed circuit board with the pushbutton actuator being retained by a tab on the end of each leg which extends beyond the edge of the slotted hole in the substrate or printed circuit board. Depressing the pushbutton flattens the curved spring washer until each edge thereof contacts two or more conductive members or portions of the printed wiring on the substrate or printed-circuit board completing an electrical circuit. Releasing the depressed pushbutton allows the spring washer to return to a normal position, opening the circuit and returning the pushbutton actuator.

In a further embodiment, a plurality of such momentary contact single pole pushbutton switches are provided on a single substrate or printed circuit board to provide a keyboard such as that utilized in a pocket or desk calculator.

Still further objects and advantages of the invention will become apparent from the detailed description and claims when read in conjunction with the accompanying drawings wherein:

FIG. 1 is an exploded view of a momentary contact single pole pushbutton switch embodied in the present invention;

FIG. 2A is a cross-sectional view of the switch of FIG.

FIG. 2B is a cross-sectional view of the switch of FIG. 1 in a plane to the cross-sectional plane of FIG. 2A;

FIG. 3 is a cross-sectional view of the embodiment of FIG. 1 showing the pushbutton actuator in the depressed position;

FIG. 4 is a top view of the conductive wave-shaped spring washer; 7

FIG. 5 is a cross-sectional view of another embodiment of the momentary contact switch in accordance with the invention; and

FIG. 6 illustrates a substrate having a plurality of momentary contact switches in accordance with the present invention to provide a keyboard.

Referring then to FIGS. 1-4, an embodiment of a momentary contact pushbutton switch in accordance with the present invention includes a pushbutton actuator 10 formed of a non-conductive material such as a molded plastic having two integral legs or projections r 11' which extend through a slot 12 in a curved waveshaped conductive spring washer 13 such as that washer 13 until the edge thereof contacts two or more conductive members 17 positioned on the substrate 15. The conductive members may be portions of the printed wiring on the upper surface 18 of the substrate 15 where the substrate is a printed circuit board. When the pushbutton actuator has been depressed and the edge of the spring washer 13 contacts the two or more conductive members 17, an electrical circuit is completed between the conductive members. Releasing the depressed pushbutton actuator 10 allows the spring washer 13 to return to a normal position opening the circuit and returning the pushbutton actuator.

The momentary contact switch in accordance with the present invention is simply manufactured by forming a slot in a substrate having two or more contacts formed thereon, forming a similar slot in a wave-shaped conductive spring washer having an outer diameter larger than the distance between the contacts, squeezing together and inserting the two integral legs of a pushbutton actuator formed of a flexible non-conductive material such as molded plastic, and having projections formed on the ends thereof through the slot in the spring washer and substrate and allowing the flexible legs to spring to a straightened position with the projections extending beyond the slot formed in the substrate thereby retaining the pushbutton actuator in the substrate.

In another embodiment of a momentary contact switch in accordance with the present invention, illustrated in FIG. 5, the conductors 17 are feedthrough conductors which feed through the substrate to provide connection on the under surface 19 of the substrate by means of a terminal 20 to spun on or soldered wire 21 or to printed wiring 21A on the bottom side of a printed circuit board comprising the substrate 15. The substrate can also be a multilayer printed circuit board having printed wiring on upper, under and/or sandwiched layers.

In the. illustrated embodiments, the curved spring washer is waveshaped forming two ends 180 apart which contact two contacts on the substrate also 180 apart. In other embodiments, the spring washer is curved at three points 120 apart to contact the two contacts on the substrate 180 apart or three contacts on the substrate 120 apart. Also, a plurality of the momentary contact switches may be mounted on a single substrate utilizing any of the embodiments described above to provide a keyboard as shown in P16. 6. The substrate may be a printed circuit board upon which a self-encoding printed circuit is provided in a manner similar to that described in US. Pat. No. 3,696,41 l for a keyboard encoder which patent is assigned to the assignee of the present invention, or US. Pat. No. 3,806,673 referenced above.

Since it is obvious that many additional changes and modifications can be made in the above-described details without departing from the nature and spirit of the invention, it is understood that the invention is not to be limited to said details except as set forth in the appended claims.

What is claimed is:

l. A momentary-contact single-pole electrical switch comprising:

a. a substrate having two major surfaces with an opening therethrough extending from one of said major surfaces to the other major surface, said substrate including a plurality of electrically con- 4 ductive terminal members on said one mzior surface approximately equidistant from said opening;

b. a non-conductive pushbutton actuator having a button and two legs with each of said legs having a retention means on the end thereof, said legs extending through said opening with said button facing said one major surface and with said retention means extending beyond the edge of said opening on said other major surface; and

c. conductive biasing means between said button and said one major surface being retained by said legs with said conductive biasing means normally biasing itself and said button away from said terminal members; wherein d. depression of said actuator button applies a force against said conductive biasing means causing said conductive biasing means to make electrical contact with said terminal members to complete a conductive path between said terminal members.

2. The electrical switch accordingto claim 1 wherein said conductive biasing means is an integral conductive curved spring member.

3. The electrical switch according to claim 2 wherein said curved spring member is a curved spring washer having an opening therein with said legs extending through such opening.

4. The electrical switch according to claim 2 wherein said curved spring member is comprised of beryllium copper.

5. The electrical switch according to claim 1 wherein said substrate is a printed circuit board.

6. The electrical switch according to claim 5 wherein said substrate includes printed wiring formed on said one major surface and said terminal members are termination points of said printed wiring.

7. The electrical switch according to claim 5 wherein said substrate includes printed wiring formed on said other major surface and said terminal members include feedthrough conductors extending through openings in said substrate and being electrically connected to said printed wiring on said other major surface of said substrate.

8. The electrical switch according to claim 1 wherein said pushbutton actuator is comprised of plastic.

9. A momentary-contact single-pole electrical switch comprising:

a. a substrate having two major surfaces and an opening therethrough extending from one of said major surfaces to the other of said major surfaces, said substrate including a plurality of electrically conductive terminal members extending on said one major surface approximately equidistant from the center of said opening;

b. a non-conductive pushbutton actuator having a button and two integral legs with each leg having an integral retainer tab on the end thereof, said legs extending through said substrate opening with said pushbutton actuator being retained by said tabs which extend beyond the edge of the opening on said other major surface; and

c. an electrically conductive spring member positioned between said button and said one major surface and having an opening therein with said legs extending through such opening, said spring member being positioned with respect to said terminal members such that the spring member is normally curved or bent away from said terminal members and biases said button; wherein spring member are non-circular and are maintained in 6 position by said legs.

11. The electrical switch according to claim 9 wherein said legs are flexible and wherein said actuator pushbutton is insertable or removable from retention by said tabs and substrate by squeezing together said flexible legs. 

1. A momentary-contact single-pole electrical switch comprising: a. a substrate having two major surfaces with an opening therethrough extending from one of said major surfaces to the other major surface, said substrate including a plurality of electrically conductive terminal members on said one major surface approximately equidistant from said opening; b. a non-conductive pushbutton actuator having a button and two legs with each of said legs having a retention means on the end thereof, said legs extending through said opening with said button facing said one major surface and with said retention means extending beyond the edge of said opening on said other major surface; and c. conductive biasing means between said button and said one major surface being retained by said legs with said conductive biasing means normally biasing itself and said button away from saiD terminal members; wherein d. depression of said actuator button applies a force against said conductive biasing means causing said conductive biasing means to make electrical contact with said terminal members to complete a conductive path between said terminal members.
 2. The electrical switch according to claim 1 wherein said conductive biasing means is an integral conductive curved spring member.
 3. The electrical switch according to claim 2 wherein said curved spring member is a curved spring washer having an opening therein with said legs extending through such opening.
 4. The electrical switch according to claim 2 wherein said curved spring member is comprised of beryllium copper.
 5. The electrical switch according to claim 1 wherein said substrate is a printed circuit board.
 6. The electrical switch according to claim 5 wherein said substrate includes printed wiring formed on said one major surface and said terminal members are termination points of said printed wiring.
 7. The electrical switch according to claim 5 wherein said substrate includes printed wiring formed on said other major surface and said terminal members include feedthrough conductors extending through openings in said substrate and being electrically connected to said printed wiring on said other major surface of said substrate.
 8. The electrical switch according to claim 1 wherein said pushbutton actuator is comprised of plastic.
 9. A momentary-contact single-pole electrical switch comprising: a. a substrate having two major surfaces and an opening therethrough extending from one of said major surfaces to the other of said major surfaces, said substrate including a plurality of electrically conductive terminal members extending on said one major surface approximately equidistant from the center of said opening; b. a non-conductive pushbutton actuator having a button and two integral legs with each leg having an integral retainer tab on the end thereof, said legs extending through said substrate opening with said pushbutton actuator being retained by said tabs which extend beyond the edge of the opening on said other major surface; and c. an electrically conductive spring member positioned between said button and said one major surface and having an opening therein with said legs extending through such opening, said spring member being positioned with respect to said terminal members such that the spring member is normally curved or bent away from said terminal members and biases said button; wherein d. depression of said pushbutton actuator causes said button to apply a force against said spring member causing said spring member to make electrical contact with said terminal members to complete a conductive path between said terminal members.
 10. The electrical switch according to claim 9 wherein said openings through said substrate and spring member are non-circular and are maintained in position by said legs.
 11. The electrical switch according to claim 9 wherein said legs are flexible and wherein said actuator pushbutton is insertable or removable from retention by said tabs and substrate by squeezing together said flexible legs. 